BIOCHEMICAL ANTAGONISM 



inactivate the metabolites. The first such protein to be studied was 

 ascorbic acid oxidase, an enzyme which is present in several plant 

 tissues and which catalyzed the oxidation, and hence the inactivation, 

 of ascorbic acid. The next example was the curious protein of egg 

 white, variously known as avidin or antibiotin, which combined 

 stoichiometrically with biotin, and thus rendered it ineffective in many 

 biological systems. This case is noteworthy, since.it involves a non- 

 enzymic process in which a specific protein is one reactant. Finally, 

 there was the enzyme system in many aquatic animals which actively 

 destroyed thiamin by splitting from it the thiazole portion of the 

 molecule. The suspicion has existed in several laboratories that these 

 proteins have roles to play in the ordered progress of metabolism, 

 and that the avidity with which they attack such vital metabolites 

 may represent only a perversion of their true functions. However, 

 there are no data to indicate their biological significance, and until 

 more is learned about them, they cannot enter further into the dis- 

 cussion of biochemical antagonisms. 



With this cursory scanning of the facts in the field of biochemical 

 antagonism, let us look about in an attempt to discover whatever light 

 may be shed on theoretical and on practical problems of biological 

 science. Particularly, let us consider some newly discernible aspects 

 of the study of metabolic mechanisms, and of the relationship of chemi- 

 cal structure to biological activity. It will be apparent as we progress 

 that there are very considerable gaps in our present scanty stock of 

 knowledge, and that in many cases these breaches are of such magni- 

 tude that, when they are eventually closed with solid knowledge, the 

 final picture which will emerge may differ rather considerably from the 

 one we are about to examine. With a field as new as this one is, there 

 are sure to be more questions than answers, and the answers available 

 are more in the nature of hypotheses than of facts. Nevertheless, let 

 us integrate present knowledge so that we may better be able to advance 



in the future. 



The first new aspect deals with the use of inhibitory structural 

 analogues of metabolites in the study of biochemical reactions. In 

 this aspect, particularly, hope exceeds realization at the present time, 

 for only local successes have been achieved. The use of specific 

 inhibition of a given reaction has been very serviceable in unraveling 

 the threads of many changes which occur. For example, fluoride 



